<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>html和css的关系</title>
    <style type="text/css">
        /*指定h1标签*/
        h1{
        font-size: 12px;
        color: aqua;
        text-align: center;
        }
    </style>
</head>
<body>
    <h1>hello world</h1>
</body>
</html>